Photovoltaic / photo-thermal / photovoltaic top cover type laminated structure

Abstract

The utility model relates to the technical field of solar energy utilization, in particular to a photovoltaic / photo-thermal / photovoltaic top cover type laminated structure and a preparation method thereof, the photovoltaic / photo-thermal / photovoltaic top cover type laminated structure comprises a rigid semitransparent photovoltaic cell, a curved-surface-shaped photo-thermal reflecting mirror and a back photovoltaic cell which are sequentially arranged from top to bottom, and the back photovoltaic cell comprises a flexible photovoltaic cell and a rigid photovoltaic cell. The system not only can effectively absorb ultraviolet light and visible light of the sun for photovoltaic power generation, but also can efficiently utilize infrared light for photo-thermal conversion through the curved-surface-shaped photo-thermal reflecting mirror, and meanwhile, the back photovoltaic cell can utilize ambient light and ground reflected light which are not absorbed by the top rigid semitransparent photovoltaic cell, so that the photovoltaic power generation efficiency is improved. And the overall energy utilization efficiency of the photo-thermal power station is further improved. Therefore, by means of structural innovation and performance optimization, efficient and comprehensive utilization of solar energy is achieved, system efficiency, light absorption capacity and service life of the battery are remarkably improved, excellent technical indexes and economic benefits are shown, and great popularization value is achieved.

Description

Technical Field

[0001] This utility model relates to the field of solar energy utilization technology, and in particular to a photovoltaic / photothermal / photovoltaic roof-type composite structure. Background Technology

[0002] With the continued growth of the global economy and the ever-expanding population, energy demand is experiencing unprecedented growth. Traditional fossil fuels, due to their limited reserves and severe environmental impacts, can no longer meet the needs of sustainable development. Therefore, the development and utilization of renewable energy has become a hot research topic globally. Solar energy, as a clean, inexhaustible, and widely distributed energy source, is of paramount importance for alleviating the energy crisis and protecting the environment.

[0003] Among solar energy utilization technologies, photovoltaic (PV) power generation and photothermal conversion are two of the most common and mature technologies. PV power generation mainly converts sunlight directly into electrical energy through photovoltaic cells, offering advantages such as high conversion efficiency and low maintenance costs. Photothermal conversion, on the other hand, utilizes sunlight to generate heat energy for various applications including heating, hot water supply, cooling, and power generation, characterized by its wide range of applications and good stability. However, relying solely on either PV or photothermal utilization methods has significant limitations in improving the overall utilization rate and efficiency of solar energy resources.

[0004] To overcome this limitation, the photovoltaic-photothermal synergistic system has emerged. This system combines photovoltaic power generation and photothermal conversion technologies to achieve a more comprehensive and efficient utilization of solar energy. The photovoltaic / photothermal superimposed structure is a prime example of this innovative approach; through ingenious design, it utilizes different wavelengths of sunlight for power generation and thermal energy conversion respectively, maximizing the utilization of solar energy resources.

[0005] However, realizing a photovoltaic / photothermal cascade structure is no easy task, facing numerous technical challenges. First, as the top element of the cascade structure, the semi-transparent photovoltaic cell needs to possess both high spectral selectivity and photoelectric conversion efficiency, while also being able to effectively transmit a certain proportion of the spectrum to provide the necessary infrared light to the underlying photothermal conversion structure. This requirement significantly increases the difficulty of developing semi-transparent photovoltaic cells.

[0006] Secondly, the design of the curved solar thermal reflector is also a major challenge. It needs to achieve an optimal balance in terms of reflection efficiency, weather resistance, and mechanical stability, while also ensuring efficient coupling with the upper semi-transparent photovoltaic cells to guarantee photothermal conversion efficiency. Furthermore, the design of the back-side photovoltaic cells is crucial, as it can further improve the overall system's photoelectric conversion efficiency by utilizing ambient light and ground-reflected light. However, existing back-side photovoltaic cells still have significant shortcomings in light capture and heat dissipation performance.

[0007] In conclusion, while photovoltaic / photothermal hybrid structures have enormous potential and application prospects, the technical challenges they face in realizing cannot be ignored.

[0008] In view of this, this utility model is proposed. Utility Model Content

[0009] The purpose of this invention is to provide a photovoltaic / photothermal / photovoltaic roof-type composite structure, which achieves efficient and comprehensive utilization of solar energy and significantly improves system efficiency, light absorption capacity and battery life.

[0010] This utility model provides a photovoltaic / photothermal / photovoltaic top cover type stacked structure, including a rigid semi-transparent photovoltaic cell, a curved photothermal reflector and a back photovoltaic cell arranged sequentially from top to bottom. The back photovoltaic cell includes any one of flexible photovoltaic cells and rigid photovoltaic cells. The flexible photovoltaic cell is closely attached to the curved photothermal reflector, and at least one point of the rigid photovoltaic cell is closely attached to the curved photothermal reflector.

[0011] As a preferred embodiment of this technical solution, a heat-conducting layer is provided on the side of the back photovoltaic cell near the curved photothermal reflector, and a light-capturing layer is provided on the inside of the back photovoltaic cell and / or on the outer surface away from the curved photothermal reflector.

[0012] As a preferred embodiment of this technical solution, the outer surface of the back photovoltaic cell away from the curved photothermal reflector is further provided with a low-reflection anti-reflection layer and a diffuse reflection scattering layer, wherein the low-reflection anti-reflection layer is close to the back photovoltaic cell or the light-catching layer.

[0013] As a preferred embodiment of this technical solution, the thermally conductive layer is a graphene film or an alumina nanosheet, and the thermally conductive layer is bonded to the back of the photovoltaic cell using a thermally conductive adhesive.

[0014] In a preferred embodiment of this technical solution, the light-harvesting layer is disposed on the outer surface of the back photovoltaic cell away from the curved photothermal reflector. The light-harvesting layer is a periodic nanopillar, nanopore array, or randomly distributed nanoparticle structure, and the material of the light-harvesting layer is indium tin oxide or zinc oxide.

[0015] As a preferred embodiment of this technical solution, the light-trapping layer is disposed on the light-absorbing layer of the back photovoltaic cell, and the light-trapping layer is a nanostructure induced by a femtosecond laser on the light-absorbing layer of the back photovoltaic cell.

[0016] In a preferred embodiment of this technical solution, the light-trapping layer is disposed in the electron transport layer of the back photovoltaic cell, and the light-trapping layer is a light-trapping nanostructure.

[0017] In a preferred embodiment of this technical solution, the light-harvesting layer is disposed between the glass and the top encapsulation layer in the back photovoltaic cell, and the light-harvesting layer is a nano-high-transmittance color film layer.

[0018] As a preferred embodiment of this technical solution, the low-reflection antireflection layer is a Bragg mirror formed by alternating deposition of high-refractive-index materials and low-refractive-index materials;

[0019] The diffuse reflection scattering layer is made of aluminum oxide or titanium dioxide nanoparticles.

[0020] As a preferred embodiment of this technical solution, the back photovoltaic cell includes either a flexible photovoltaic cell or a rigid photovoltaic cell, wherein the flexible photovoltaic cell is tightly attached to the curved photothermal reflector, and at least one point of the rigid photovoltaic cell is tightly attached to the curved photothermal reflector.

[0021] The photovoltaic / photothermal / photovoltaic roof-type composite structure of this utility model has at least the following beneficial effects:

[0022] This invention's photovoltaic / photothermal / photovoltaic top-mounted stacked structure effectively integrates rigid semi-transparent photovoltaic cells, curved photothermal reflectors, and back-mounted photovoltaic cells, achieving efficient distribution and utilization of the solar spectrum. This system not only effectively absorbs ultraviolet and visible light from the sun for photovoltaic power generation but also efficiently utilizes infrared light for photothermal conversion through the curved photothermal reflectors. Simultaneously, the back-mounted photovoltaic cells can utilize ambient light and ground-reflected light not absorbed by the top rigid semi-transparent photovoltaic cells, further improving the overall energy efficiency of the solar thermal power plant. Furthermore, this invention includes a heat-conducting layer on the side of the back-mounted photovoltaic cells closest to the curved photothermal reflectors, effectively ensuring the stability of the overall structure and the long-term efficient operation of the cells. Additionally, a light-harvesting layer is provided inside the back-mounted photovoltaic cells and / or on the outer surface away from the curved photothermal reflectors, significantly improving the light absorption capacity of the back-mounted photovoltaic cells.

[0023] Studies have shown that the photovoltaic / photothermal / photovoltaic hybrid structure of this invention performs well under typical solar radiation conditions (illuminance of 1000 W / m²). 2 The total energy conversion efficiency (based on the standard AM1.5 spectrum) can reach 45%-50%, which is 10%-20% higher than the average efficiency (25%-35%) of traditional split photovoltaic or solar thermal systems. Among them, the photoelectric conversion efficiency of the upper rigid semi-transparent photovoltaic cells for ultraviolet and visible light can reach 15%-20%.

[0024] Furthermore, the utilization rate of ambient light and ground-reflected light by the back-side photovoltaic cells is improved by 20%-30%. Combined with the nanostructured light-trapping layer design, the light absorption capacity of the back-side photovoltaic cells is increased by 10%-15% compared to ordinary cells without a light-trapping layer, resulting in an increase in power generation efficiency of approximately 5%-8%. Experimental data shows that at an ambient light intensity of 200W / m²... 2 Under low light conditions, the additional power generation of the back photovoltaic cells accounts for 8%-10% of the total power generation of the system, significantly enhancing the low-light performance of the overall system.

[0025] In terms of thermal management, the adoption of a thermally conductive layer design reduces the operating temperature of the photovoltaic cell by 15-20°C compared to traditional designs. According to accelerated life testing results, this temperature reduction effectively extends the lifespan of the photovoltaic cell, increasing fatigue life by 25%-30%. For example, under continuous operation at 70°C, the efficiency of ordinary photovoltaic cells decreases by approximately 5% due to thermal degradation, while the efficiency of the photovoltaic cell of this invention decreases by only 2%.

[0026] In summary, this utility model achieves efficient and comprehensive utilization of solar energy through structural innovation and performance optimization, and significantly improves system efficiency, light absorption capacity and battery life, demonstrating superior technical indicators and economic benefits, and is of great promotional value. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the photovoltaic / photothermal / photovoltaic top-cover composite structure of this utility model (the photovoltaic cell on the back is a flexible photovoltaic cell);

[0029] Figure 2 This is one of the schematic diagrams of the photovoltaic / photothermal / photovoltaic top-cover type stacked structure of this utility model (the photovoltaic cell on the back is a rigid photovoltaic cell);

[0030] Figure 3 This is the second schematic diagram of the photovoltaic / photothermal / photovoltaic top cover composite structure of this utility model (the photovoltaic cell on the back is a rigid photovoltaic cell);

[0031] Figure 4 This is the third schematic diagram of the photovoltaic / photothermal / photovoltaic top cover composite structure of this utility model (the photovoltaic cell on the back is a rigid photovoltaic cell);

[0032] Figure 5This is the fourth schematic diagram of the photovoltaic / photothermal / photovoltaic top cover composite structure of this utility model (the photovoltaic cell on the back is a rigid photovoltaic cell);

[0033] Figure 6 This is one of the structural schematic diagrams of the back photovoltaic cell of this utility model;

[0034] Figure 7 This is the second schematic diagram of the structure of the back photovoltaic cell of this utility model;

[0035] Figure 8 This is the third schematic diagram of the structure of the photovoltaic cell on the back of this utility model.

[0036] Figure label:

[0037] 1: Rigid semi-transparent photovoltaic cell; 2: Back photovoltaic cell; 3: Curved photothermal reflector; 4: Support frame; 5: Sunlight; 6: Infrared light; 7: Heat collector; 8: Thermal conductive layer; 9: Light capturing layer; 10: Low-reflection anti-reflection layer; 11: Diffuse reflection scattering layer; 12: Encapsulation layer; 13: Top electrode; 14: Electron transport layer; 15: Light absorption layer; 16: Bottom electrode; 17: Substrate. Detailed Implementation

[0038] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0041] Example 1

[0042] like Figure 1-8As shown, this embodiment provides a photovoltaic / photothermal / photovoltaic top-cover type stacked structure, including a rigid semi-transparent photovoltaic cell 1, a curved photothermal reflector 3, and a back photovoltaic cell 2 arranged sequentially from top to bottom. The back photovoltaic cell 2 has a heat-conducting layer 8 on the side close to the curved photothermal reflector 3, and a light-capturing layer 9 is provided on the interior and / or the outer surface of the back photovoltaic cell 2 away from the curved photothermal reflector 3.

[0043] In the photovoltaic / photothermal / photovoltaic roof-mounted cascade structure of this embodiment, a rigid semi-transparent photovoltaic cell 1 is mounted on a curved photothermal reflector 3, and a back photovoltaic cell 2 is directly fabricated or attached to the curved reflector. When sunlight 5 shines on the rigid semi-transparent photovoltaic cell 1, ultraviolet and visible light are absorbed by the rigid semi-transparent photovoltaic cell 1, while infrared light 6 is reflected by the curved photothermal reflector 3 to the collector 7 and absorbed. The back photovoltaic cell 2 can further absorb ambient light and ground-reflected light. Furthermore, a solar tracking axis can be provided in the photovoltaic / photothermal / photovoltaic roof-mounted cascade structure of this embodiment. The solar tracking axis can adjust the orientation of the photovoltaic cells to receive as much sunlight 5 as possible.

[0044] This invention integrates two layers of photovoltaic cells on a curved solar thermal reflector 3. Visible light is absorbed by the top-mounted rigid semi-transparent photovoltaic cell 1 and converted into electrical energy, while infrared light 6 passes through the top-mounted rigid semi-transparent photovoltaic cell 1 and enters the curved solar thermal reflector 3 for photothermal conversion, maximizing the comprehensive utilization rate of solar energy. The back photovoltaic cell 2 can be used to absorb unused ambient light and ground-reflected light. Therefore, through the synergistic effect of the rigid semi-transparent photovoltaic cell 1, the curved solar thermal reflector 3, and the back photovoltaic cell 2, this invention achieves a triple benefit of photovoltaic power generation and photothermal utilization, significantly improving the overall energy utilization efficiency of the curved reflector-type solar thermal power plant and realizing efficient utilization of the spectrum.

[0045] In this embodiment, the rigid semi-transparent photovoltaic cell 1 comprises, from bottom to top, a high-transparency glass substrate, a first transparent electrode, a first interface modification layer, a hole transport layer / electron transport layer, a second interface modification layer, a semi-transparent light absorption layer, a third interface modification layer, an electron transport layer / hole transport layer, a fourth interface modification layer, a second transparent electrode, an encapsulation layer, and an anti-reflection layer. One or more of the first interface modification layer, hole transport layer / electron transport layer, second interface modification layer, third interface modification layer, electron transport layer / hole transport layer, fourth interface modification layer, and anti-reflection layer may be absent.

[0046] In this embodiment, the curved light and heat reflector 3 includes, from bottom to top, a base layer, a reflective layer (including one or more layers of metals such as silver / copper), and glass (including float glass, ultra-clear glass, low-iron glass, high-strength tempered glass, etc.).

[0047] Furthermore, to further improve the photothermal reflection efficiency and structural stability of the curved photothermal reflector 3, a first reflective film layer, a heat insulation layer, a second reflective film layer, a protective layer, an anti-reflection layer, and a dustproof self-cleaning layer can be added. In this case, the curved photothermal reflector 3, from bottom to top, includes a base layer, a first reflective film layer, a heat insulation layer, a second reflective film layer, a protective layer, an anti-reflection layer, and a dustproof self-cleaning layer.

[0048] The first reflective film layer is located above the base layer and employs a high-reflectivity metal coating (such as silver or aluminum), and undergoes nano-processing to enhance its ability to reflect infrared light. The main function of this film layer is to efficiently reflect infrared light in the spectrum, thereby concentrating heat energy more efficiently into the photothermal system and improving photothermal efficiency.

[0049] The heat insulation layer is used to create a heat insulation effect between the substrate layer and the first reflective film layer, preventing heat caused by high temperatures from being transferred to the substrate material. High-temperature resistant, low thermal conductivity materials, such as ceramic matrix composites or aerogels, are typically used to effectively insulate heat and prevent heat diffusion to the reflective substrate layer. This layer design helps the photothermal system operate stably at high temperatures and extends the service life of the substrate layer of the curved photothermal reflector 3.

[0050] The second reflective film layer is immediately adjacent to the heat insulation layer and typically employs a multilayer dielectric film structure to enhance its reflective properties. This layer further improves the reflectivity of visible and infrared light through multiple reflections and focusing of light, ensuring that the light energy in the system is utilized to the maximum extent.

[0051] The protective layer is located above the second reflective film layer and is made of anti-oxidation and anti-corrosion materials (such as silicon dioxide or silicon nitride) to protect the reflective layer from environmental influences (such as moisture, acids and alkalis, temperature fluctuations, etc.).

[0052] The antireflection layer is used to reduce the reflection loss of light caused by interface refraction on the surface of the curved photothermal reflector 3. This layer is preferably made of a low refractive index material, such as magnesium fluoride or aluminum oxide nanolayers, which can improve the overall optical antireflection effect. This structure can also improve the incident angle range of light, so that the optical performance of the curved photothermal reflector 3 can be fully utilized under different illumination angles.

[0053] The dustproof self-cleaning layer, made of superhydrophobic or superhydrophilic materials, can optionally employ a nanostructured self-cleaning coating to prevent the adhesion of dust, rainwater, and contaminants, reducing cleaning frequency and maintenance costs. This layer is particularly suitable for outdoor dusty environments, effectively improving the reflectivity of the curved light and heat reflector 3 under prolonged outdoor exposure.

[0054] In this embodiment, the back photovoltaic cell 2 includes either a flexible photovoltaic cell or a rigid photovoltaic cell. The flexible photovoltaic cell is tightly attached to the curved photothermal reflector 3, while the rigid photovoltaic cell has at least one point tightly attached to the curved photothermal reflector 3, preferably at the lowest point of the curved photothermal reflector 3, to ensure structural stability. The flexible photovoltaic cell includes any one of the following: perovskite solar cells, organic solar cells, copper indium gallium selenide (CIGS) photovoltaic cells, flexible dye-sensitized solar cells, flexible monocrystalline silicon solar cells, amorphous silicon flexible cells, flexible cadmium telluride (CdTe) solar cells, and quantum dot solar cells. The rigid photovoltaic cell includes any one of the following: silicon solar cells, perovskite solar cells, CdTe solar cells, gallium arsenide (GaAs) solar cells, organic solar cells, quantum dot solar cells, and CIGS solar cells. In addition, rigid photovoltaic cells can also form V-shaped, L-shaped, and U-shaped structures, including various structural forms such as horizontal single-panel back photovoltaic cells, oblique single-panel back photovoltaic cells, oblique multi-panel back photovoltaic cells, and horizontal oblique multi-panel back photovoltaic cells.

[0055] In addition, a heat-conducting layer 8 is provided on the side of the back photovoltaic cell 2 closest to the curved photothermal reflector 3, and a light-harvesting layer 9 is provided on the inner side of the back photovoltaic cell 2 and / or the outer surface on the side furthest from the curved photothermal reflector 3. The heat-conducting layer 8 can accelerate heat dissipation through a material with high thermal conductivity, reduce the cell's operating temperature, and extend its service life; while the light-harvesting layer 9 can improve the absorption efficiency of the back photovoltaic cell 2 for ambient light and ground-reflected light, and optimize the light path extension and scattering.

[0056] Specifically, the thermally conductive layer 8 can be made of graphene film or alumina nanosheets with high thermal conductivity, which can be achieved through sputtering or lamination techniques. The back photovoltaic cell with the thermally conductive layer 8 is then firmly bonded to the curved photothermal reflector 3 using a thermally conductive adhesive (such as silver paste or silicone), and the bonding strength is ensured by vacuum hot pressing.

[0057] The light-harvesting layer 9 can be located inside the back photovoltaic cell 2, or it can be located on the outer surface of the back photovoltaic cell 2 away from the curved photothermal reflector 3.

[0058] When the light-harvesting layer 9 is disposed on the outer surface of the back photovoltaic cell 2 away from the curved photothermal reflector 3, the light-harvesting layer 9 can be a periodic nanopillar, nanopore array or randomly distributed nanoparticle structure to achieve broadband light absorption, and the material of the light-harvesting layer 9 can be a transparent conductive material such as indium tin oxide or zinc oxide.

[0059] Its preparation method is as follows:

[0060] A layer of polymer mask material (such as PMMA) is spin-coated on the surface of the back photovoltaic cell 2. Nanostructure patterns are generated on the mask material using electron beam lithography or laser interference lithography. The patterns are then transferred to the surface of the back photovoltaic cell 2 through plasma etching to form periodic nanostructures.

[0061] In practical applications, the size of periodic nanostructures can be optimized according to the wavelength of the target spectrum. For example, the size range of periodic nanopillars is 50-200 nm, the spacing is 100-300 nm, and the height is 100-500 nm.

[0062] When the light-harvesting layer 9 is placed in the light-absorbing layer 15 of the back photovoltaic cell 2, a femtosecond laser is used to induce the formation of nanostructures inside the light-absorbing layer 15 of the back photovoltaic cell 2. By studying the dynamic process and mechanism of femtosecond laser inducing the formation of nanostructures inside silicon, the shape and size of the femtosecond laser-induced nanostructures can be controlled. During the preparation process, different atmospheres, temperatures, thermal annealing and other methods can be combined to improve the carrier mobility of the nanostructure silicon material, thereby expanding the infrared absorption spectrum of the silicon material.

[0063] When the light-trapping layer 9 is disposed in the electron transport layer 14 of the back photovoltaic cell 2, ZnO with a light-trapping nanostructure is used as the electron transport layer 14 of the back photovoltaic cell 2.

[0064] Its preparation method is as follows:

[0065] First, a suitable substrate material 17 was selected, and a ZnO seed layer was deposited on it to provide a basis for the subsequent growth of nanopillars;

[0066] Next, Mg-doped ZnO nanopillars are grown on the seed layer using techniques such as chemical vapor deposition (CVD), physical vapor deposition (PVD), or hydrothermal methods.

[0067] Doping with Mg can improve the light scattering ability of ZnO in the 300-430nm wavelength range. This is because the introduction of Mg will change the band structure of ZnO, thereby affecting its light absorption and scattering characteristics.

[0068] Before or after the growth of ZnO nanopillars, the seed layer is annealed. The annealing temperature and time need to be precisely controlled to optimize the crystallinity of the seed layer, improve the growth quality of the ZnO nanopillars, and regulate the broad-spectrum scattering ability. This process allows for controllable scattering ability of the ZnO nanopillar film across a broad spectral range of 300-850 nm.

[0069] Based on the ZnO nanopillar film, an Al-doped ZnO film is further deposited. Al doping can improve the electrical conductivity of the film while maintaining its light scattering ability.

[0070] Next, the Al-doped ZnO thin film underwent a two-step annealing process. The first annealing step aimed to remove residual stress and defects in the film and stabilize its structure; the second annealing step further improved the film's crystallinity and electrical conductivity. By precisely controlling the temperature and time of the two-step annealing, an Al-doped ZnO thin film with an electrical conductivity of 2.76e-03 S / cm and good light scattering ability could be obtained.

[0071] The ZnO nanopillar film and Al-doped ZnO film processed by the above steps are combined to form a light-trapping ZnO nanostructure light-harvesting layer 9, which serves as an electron transport layer 14 and is located between the active layer and the top electrode 13 of the photovoltaic cell.

[0072] The light-trapping ZnO nanostructure light-harvesting layer 9 utilizes its unique nanostructure and light-scattering properties, combined with the back reflective electrode of the battery, to increase the optical path of light in the active layer through light scattering and multiple reflections, thereby improving the light absorption efficiency and thus enhancing the photoelectric conversion performance of the photovoltaic cell.

[0073] When the light-harvesting layer 9 is disposed between the glass and the top encapsulation layer 12 in the back photovoltaic cell 2, a nano-metal oxide high-transmittance color film layer is used as the light-harvesting layer 9.

[0074] Its preparation method is as follows:

[0075] Under nitrogen protection, sulfur source, zinc salt, cadmium salt, noble metal nanoparticles, and surface modifier are added to a polar organic solvent in one step, and the reaction mixture is reacted at 180-200℃ for 10-15 hours.

[0076] The surface-modified nanoparticles are precipitated using a poor solvent, and after centrifugation, washing, and drying, a solid powder of surface-modified nanoparticles is obtained.

[0077] Nanoparticle solid powder and additives are mixed evenly in proportion, then plasticized by screw extrusion, flowed out from the die head, and pressed by rollers to obtain a high-transparency color film layer of nano metal oxide;

[0078] The nano-metal oxide high-transmittance color film layer is attached to the glass surface through a casting process. It is located between the glass and the top encapsulation layer 12. By utilizing its strong optical interference effect on light, the loss of light when it shines from the top EVA film onto the battery cell is reduced, thereby improving power generation efficiency.

[0079] Based on the above technical solution, and further preferably, a low-reflection anti-reflection layer 10 and a diffuse reflection scattering layer 11 are also provided on the outer surface of the back photovoltaic cell 2 away from the curved photothermal reflector 3, wherein the low-reflection anti-reflection layer 10 is close to the back photovoltaic cell 2 or the light-capturing layer 9.

[0080] When a light-capturing layer 9 is provided on the outer surface of the back photovoltaic cell 2 away from the curved photothermal reflector 3, the light-capturing layer 9, the low-reflection anti-reflection layer 10, and the diffuse reflection scattering layer 11 are sequentially disposed on the surface of the back photovoltaic cell 2 from the inside out.

[0081] When a light-harvesting layer 9 is provided inside the back photovoltaic cell 2, a low-reflection anti-reflection layer 10 and a diffuse reflection scattering layer 11 are sequentially disposed on the surface of the back photovoltaic cell 2 from the inside out.

[0082] When both the inner and outer surfaces of the back photovoltaic cell 2 are provided with light-harvesting layers 9, the low-reflection anti-reflection layer 10 and the diffuse reflection scattering layer 11 are sequentially disposed on the surface of the back photovoltaic cell 2 from the inside out.

[0083] Specifically, the low-reflection antireflection layer 10 is a Bragg mirror formed by alternating deposition of high-refractive-index materials (such as titanium dioxide) and low-refractive-index materials (such as silicon dioxide) to further reduce light reflection loss.

[0084] The specific preparation method is as follows:

[0085] Select a suitable substrate material and perform cleaning and treatment to ensure that the deposited film has good adhesion and uniformity;

[0086] A layer of high refractive index material (such as titanium dioxide) is deposited on the substrate using appropriate deposition techniques (such as electron beam evaporation, ion beam sputtering, or atomic layer deposition).

[0087] Deposit a layer of low-refractive-index material (such as silicon dioxide) on a high-refractive-index material;

[0088] Repeat steps 2 and 3 as needed to form a multi-layered Bragg reflector;

[0089] The deposited Bragg reflector undergoes necessary annealing, cleaning, and testing to ensure it has good optical performance and stability.

[0090] Specifically, the diffuse reflection scattering layer 11 is made of aluminum oxide or titanium dioxide nanoparticles, which are mainly coated on the back shell of the back photovoltaic cell 2 to improve the rescattering efficiency of ground reflected light.

[0091] Example 2

[0092] This embodiment provides a method for fabricating a photovoltaic / photothermal / photovoltaic top cover stacked structure, wherein the method for fabricating the top cover structure of the rigid semi-transparent photovoltaic cell 1 is as follows:

[0093] S1. Selection of high-transparency glass substrate

[0094] High-transmittance low-iron glass or ultra-clear glass should be selected, preferably glass coated with indium tin oxide (ITO) or calcium fluoride to increase the transmittance of ultraviolet and visible light. The thickness of the high-transmittance glass substrate is 1-2 mm, selected according to the mechanical strength requirements. Polished glass substrates can be used directly as substrates after cleaning and drying. Alternatively, an anti-reflective coating can be formed on the glass surface using vacuum deposition to enhance weather resistance and optical properties, depending on the requirements.

[0095] S2. Fabrication of the first transparent electrode layer

[0096] Indium tin oxide (ITO) or aluminum zinc oxide (AZO) is used as the first transparent electrode layer, preferably ITO, to ensure conductivity and light transmittance. The thickness of the first transparent electrode layer is 80-100 nm. It can be deposited on a high-transmittance glass substrate using magnetron sputtering or electron beam evaporation. After deposition, heat treatment is performed at 200-300°C to improve the conductivity and transparency of the electrode.

[0097] S3. Preparation of the hole transport layer

[0098] The hole transport layer can be made of PEDOT:PSS or PTAA (polytriphenylamine), with a thickness of 20-40 nm. It can be prepared by spin coating or vapor deposition and cured at low temperature.

[0099] S4. Preparation of the light absorption layer

[0100] A wide-bandgap perovskite compound with a bandgap range of 1.62 eV to 2.5 eV and a thickness of 300-700 nm was selected. Specifically, a solution spin-coating method was used, in which the perovskite precursor solution was uniformly mixed and then coated onto the interface modification layer using a slit coating method. Subsequently, a heat treatment at 100-150℃ was performed to crystallize the film and form a uniform and dense perovskite light-absorbing layer.

[0101] S5, Fabrication of the electron transport layer

[0102] The electron transport layer can be made of fullerene C 60 Alternatively, PCBM, with a thickness of 20-40 nm, can be prepared by spin coating or vapor deposition followed by heat treatment at 80-100℃.

[0103] S6, Second transparent electrode layer

[0104] Indium tin oxide (ITO) or aluminum zinc oxide (AZO) is used as the second transparent electrode layer, with a thickness of 80-100 nm. The transparent electrode layer can be deposited on the electron transport layer using magnetron sputtering or electron beam evaporation to form a complete electrode structure.

[0105] S7, encapsulation layer and anti-reflective layer

[0106] The encapsulation layer uses epoxy resin or polyvinylidene fluoride (PVDF), while the antireflective layer is magnesium fluoride (MgF2) or a multilayer nano-antireflective coating. The encapsulation layer has a thickness of 0.5-1 mm, and the antireflective layer has a thickness of 50-100 nm. The outermost layer is coated with a nanomaterial or low-refractive-index material with high antireflective properties, such as magnesium fluoride or nanostructured alumina, to reduce light reflection and improve the utilization efficiency of incident light. Specifically, the encapsulation layer can be formed into a uniform protective film by drop coating or spin coating, which ensures sealing performance after curing; the antireflective layer can be prepared by vacuum deposition or thermal evaporation to control light transmittance.

[0107] The materials and preparation methods of the first interface modification layer, the second interface modification layer, the third interface modification layer and the fourth interface modification layer can be referred to the existing technology, and will not be repeated here.

[0108] The fabrication method of the curved optical-thermal reflector 3 is as follows:

[0109] T1, Selection of the basal layer

[0110] The base layer can be made of lightweight, high-strength aluminum alloys (such as 6061 or 7075 aluminum alloys), composite materials (such as carbon fiber composites), or high-temperature resistant plastics (such as polyimide). It can be formed by stamping or hot pressing to ensure material uniformity and strength, with a thickness of 3-10 mm, depending on the structural requirements of the design.

[0111] The base layer provides structural support for the photothermal reflector, ensuring its stability under high temperatures and harsh weather conditions.

[0112] T2. Preparation of the first reflective film layer

[0113] High-reflectivity metals (such as silver or aluminum), typically in nanoscale films, are used to enhance infrared light reflection, with a thickness of 50-150 nm. These films can be prepared via vacuum evaporation or magnetron sputtering and further nanofabrication to improve reflectivity.

[0114] The first reflective film layer mainly improves the efficiency of the photothermal system by reflecting infrared light.

[0115] T3, Preparation of the heat insulation layer

[0116] High-temperature resistant materials with low thermal conductivity are selected, such as ceramic matrix composites (alumina-based ceramics) or aerogels, with a thickness of 1-5 mm. Aerogels are applied using spraying or thermal spraying techniques, while ceramic matrix composites are applied using sintering techniques.

[0117] The insulation layer is mainly used to prevent heat from being transferred to the base layer at high temperatures, thus extending the life of the base layer.

[0118] T4. Preparation of the second reflective film layer

[0119] A multilayer dielectric film structure is employed, typically a combination of materials such as SiO2 and TiO2, to control the reflection and transmission spectral characteristics. Each layer is approximately 50-200 nm thick, and the total thickness of the entire multilayer film can reach 500-1000 nm. Specifically, physical vapor deposition (PVD) or chemical vapor deposition (CVD) methods can be used to deposit the multilayer film structure on top of the thermal insulation layer.

[0120] The second reflective film layer is mainly used to enhance the reflectivity of visible light and infrared light, thereby maximizing the utilization of light energy.

[0121] T5. Preparation of Anti-reflective Layer

[0122] Low refractive index materials, such as magnesium fluoride (MgF2) or aluminum oxide (Al2O3) nanolayers, with a thickness of 100-150 nm, are typically uniformly coated onto the protective layer using sputtering or evaporation processes.

[0123] Anti-reflective coatings primarily enhance light transmittance and improve overall optical performance by reducing light reflection loss caused by interface refraction.

[0124] The curved solar thermal reflector 3 of this invention integrates the functions of each layer, effectively improving the reflection efficiency and durability of the solar thermal reflector, and meeting the requirements of the photovoltaic / solar thermal top-mounted coupling structure.

[0125] The following is the fabrication method of the back photovoltaic cell 2:

[0126] (1) When flexible perovskite photovoltaic cells are used as the back photovoltaic cell 2, the preparation method is as follows:

[0127] a. Selection of flexible substrate 17

[0128] Polyimide (PI) or polyethylene terephthalate (PET) is used as the flexible substrate 17. The substrate 17 needs to be cleaned (ultrasonic water washing, acetone and isopropanol cleaning) and subjected to plasma treatment to improve surface adhesion;

[0129] b. Fabrication of bottom electrode 16

[0130] A transparent conductive oxide (such as ITO or FTO) layer is deposited on a flexible substrate 17 by magnetron sputtering, and the deposition thickness is controlled to be 100-200 nm to ensure conductivity and light transmittance.

[0131] c. Preparation of the perovskite layer

[0132] A perovskite precursor solution was prepared and coated onto the bottom electrode 16 using a slit coating process. The solution was then annealed by gradient heating (e.g., 70°C, 100°C, and 150°C) to form a dense perovskite film.

[0133] d. Fabrication of Electron Transport Layer 14 (ETL)

[0134] PCBM, SnO2, or TiO2 are selected as electron transport materials and deposited by solution method (spin coating) or vacuum evaporation method;

[0135] e. Fabrication of top electrode 13

[0136] A layer of metal (such as Ag or Au) is deposited by vapor deposition, or Ag nanowires are deposited by magnetron sputtering as the top electrode 13.

[0137] f. Packaging Processing

[0138] Encapsulation with UV-curable resin or flexible film protects the battery from water and oxygen corrosion.

[0139] (2) When flexible organic photovoltaic cells (OPVs) are used as the back photovoltaic cell 2, the preparation method is as follows:

[0140] a. Selection of flexible substrate 17

[0141] PET or polybutylene terephthalate (PBT) is used as the substrate 17, and its surface treatment method is the same as that of flexible perovskite photovoltaic cells.

[0142] b. Fabrication of bottom electrode 16

[0143] Use ITO, graphene, or flexible metal mesh (such as Ag NWs) as the bottom electrode 16;

[0144] c. Preparation of the active layer

[0145] Prepare a P3HT:PCBM mixed solution (or other high-efficiency donor / acceptor material system) and apply it to the bottom electrode 16 by blade coating, spraying or spin coating process;

[0146] d. Fabrication of Electron / Hole Transport Layer (ETL / HTL)

[0147] The electron transport layer 14 can be ZnO or TiO2, and the hole transport layer can be PEDOT:PSS. Both can be prepared by spraying or spin coating.

[0148] e. Fabrication of top electrode 13

[0149] A thin layer of metal (such as Al or Ag) is used as the top electrode 13, with a thickness of 50-100 nm, to ensure flexibility;

[0150] f. Packaging Processing

[0151] Use a flexible, transparent film for encapsulation to avoid mechanical damage and environmental corrosion.

[0152] (3) When a flexible heterojunction silicon photovoltaic cell is selected as the back photovoltaic cell 2, its preparation method is as follows:

[0153] a. Silicon wafer fabrication

[0154] Thin crystalline silicon (50 μm thick) can be selected to prepare flexible silicon wafers by cutting or chemical etching, or flexible amorphous silicon can be prepared by pyrolysis.

[0155] b. Preparation of heterostructures

[0156] A thin film (such as silicon nitride or silicon oxide) is deposited on the surface of a silicon wafer using chemical vapor deposition (CVD) as a passivation layer, and then an electron or hole transport material (such as PEDOT:PSS or TiO2) is prepared by solution coating.

[0157] c. Electrode preparation

[0158] Ag or Cu thin films are used as electrodes, deposited by spraying or magnetron sputtering, and the battery area is divided by laser patterning to improve efficiency.

[0159] d. Packaging Processing

[0160] Encapsulation using a high-temperature resistant and flexible polymer film.

[0161] (4) When flexible quantum dot photovoltaic cells are used as the back photovoltaic cell 2, the preparation method is as follows:

[0162] a. Fabrication of ZnO nanosheet arrays grown on titanium mesh

[0163] Cleaning the titanium mesh: Place the cut titanium mesh in a beaker containing concentrated hydrochloric acid and ultrasonically clean it for 10 minutes. Then clean it twice with deionized water and alcohol in sequence, and finally dry it in nitrogen at room temperature.

[0164] Preparation and coating of seed solution: Mix 0.02M zinc acetate and 0.02M lithium hydroxide, stir and dissolve to obtain ZnO seed solution; gently immerse the cleaned titanium mesh in the seed solution with tweezers, shake for about 1 minute, take it out, shake off the surface liquid, place it in nitrogen to dry the remaining moisture, and then anneal it in a sintering furnace at 350℃ for 15 minutes.

[0165] Growth of ZnO nanosheet array structure: 0.2M zinc nitrate and 1M urea were dissolved in deionized water to obtain ZnO growth solution. A titanium mesh with a seed layer was placed tilted in a reaction vessel, and the growth solution was poured in to completely immerse the titanium mesh. The mixture was heated at 90℃ for 12 hours in a drying oven, removed, rinsed with deionized water, air-dried at room temperature, and then annealed at 450℃ for 1 hour.

[0166] b. Preparation of ZnO / ZnSe / CdSe electrodes

[0167] Preparation of ZnO / ZnSe electrode: A titanium mesh with ZnO nanosheets grown on it was immersed in a Se solution containing 12 mM selenium powder and 24 mM sodium borohydride. 2- In an aqueous solution containing ions, incubate at 55°C for 30 minutes;

[0168] Preparation of ZnO / ZnSe / CdSe electrode: The ZnO / ZnSe electrode was placed in a solution containing 80 mM cadmium nitrate and kept at 55 °C for 15 min to 4 h to obtain CdSe nanolayers of different thicknesses. Finally, it was washed with deionized water and dried in air at 60 °C.

[0169] Preparation of polysulfide solid electrolyte: Dissolve 1M sodium sulfide, 1M elemental sulfur and 0.1M sodium hydroxide in deionized water and stir at 80℃ for 2 hours to obtain a transparent orange-red liquid, which is the electrolyte.

[0170] c. Preparation of Cu₂S counter electrode

[0171] After cutting the 0.5mm thick copper sheet into small pieces, polish them on sandpaper to remove the surface oxide layer. Then, place them in a concentrated hydrochloric acid solution at 70℃ for 10 minutes. After removing them, rinse them with deionized water to remove the hydrochloric acid. Then, use a dropper to evenly drip polysulfide solid electrolyte onto the cleaned copper sheet surface until the copper sheet surface turns a uniform black.

[0172] d. Perform battery packaging

[0173] A 0.25cm hole was drilled in a 60μm thick encapsulation film using a punch. 2 Make a small hole, stick it to both sides of the photoanode and let it dry. Place a flexible transparent film and a Cu2S counter electrode on the top and bottom of the photoanode respectively. Finally, drip polysulfide solid electrolyte into the gap between the two electrodes.

[0174] (5) When using a monocrystalline silicon cell (rigid) as the back photovoltaic cell 2, a high-efficiency monocrystalline silicon photovoltaic cell can be prepared using a high-purity silicon ingot through steps such as slicing, surface treatment, and doping. The preparation method is as follows:

[0175] a. Silicon wafer cutting

[0176] Silicon wafers with a thickness of approximately 150-200μm are cut from high-purity single-crystal silicon ingots. Diamond wire cutting can be used to ensure slicing accuracy and surface flatness.

[0177] b. Surface cleaning and texturing

[0178] Chemical solutions (such as KOH or HF) are used to remove the oxide layer and impurities on the surface of the silicon wafer, and pyramid-shaped microstructures are formed by alkaline or acidic solutions to reduce reflectivity.

[0179] c. Diffusion doping

[0180] Phosphorus or boron is diffused in a high-temperature furnace to form a pn junction, and the diffusion depth and concentration are controlled to optimize battery performance;

[0181] d. Surface passivation

[0182] By depositing silicon nitride (SiN) x Passivation with H or alumina (Al2O3) thin films can reduce surface recombination loss.

[0183] e. Electrode printing and sintering

[0184] Silver paste (positive electrode) and aluminum paste (back electrode) are printed using screen printing technology and sintered at a high temperature of 800-900℃ to form ohmic contacts.

[0185] (6) When polycrystalline silicon cells (rigid) are selected as the back photovoltaic cells 2, polycrystalline silicon ingots are prepared by casting method, and polycrystalline silicon photovoltaic cells are prepared by process similar to that of monocrystalline silicon.

[0186] (7) When a perovskite photovoltaic cell (rigid) is selected as the back photovoltaic cell 2, it can be prepared based on an organic-inorganic hybrid perovskite material (such as MAPbI3 or CsPbBr3) through a solution processing process. The preparation method is as follows:

[0187] a. Base 17 Cleaning

[0188] A conductive layer (such as ITO) is deposited on a glass or rigid substrate 17;

[0189] b. Perovskite layer preparation

[0190] Perovskite precursor solutions with a band gap range of 1.1 eV-2.3 eV are deposited by spin coating or spray coating, and perovskite crystal growth is promoted by thermal annealing.

[0191] c. Interface layer deposition

[0192] Electron transport layer 14 (such as TiO2 or SnO2) and hole transport layer (such as Spiro-OMeTAD or PEDOT:PSS) are deposited sequentially.

[0193] d. Metal electrode coating

[0194] Use vacuum evaporation or sputtering to deposit metal electrodes (such as Au or Ag);

[0195] e. Packaging

[0196] Encapsulation with transparent epoxy resin or glass cover improves stability.

[0197] (8) When copper indium gallium selenide (CIGS) cells (rigid) are used as the back photovoltaic cell 2, the preparation method is as follows:

[0198] a. Base 17 selection

[0199] A Mo back electrode is deposited on a rigid substrate 17 (such as glass or a metal sheet);

[0200] b. CIGS thin film deposition

[0201] Cu, In, Ga, and Se elements are deposited using co-evaporation or sputtering techniques;

[0202] c. Buffer layer deposition

[0203] A CdS buffer layer was deposited using a chemical bath method;

[0204] d. Coating of transparent conductive layer

[0205] Deposit ZnO or ITO as a transparent conductive layer;

[0206] e. Electrode fabrication and packaging

[0207] The battery area is delineated and electrodes are added, followed by encapsulation for protection. The encapsulation method is similar to the previous one.

[0208] Different types of rigid photovoltaic cell fabrication methods vary depending on material properties and application requirements. The specific choice should take into account efficiency, cost, process complexity and application scenario.

[0209] The improvements to the back photovoltaic cell 2 of this utility model (the introduction of thermal conductive layer 8, light capturing layer 9, low reflection anti-reflection layer 10 and diffuse reflection scattering layer 11) are all made by preparing the corresponding improved layers on the surface or in the middle layer after the above basic components are prepared. The specific preparation method can be referred to the above content.

[0210] The fabrication method of the photovoltaic / photothermal / photovoltaic roof-type composite structure in this embodiment is as follows:

[0211] The rigid semi-transparent photovoltaic cell 1 is mounted on top of the curved photothermal reflector 3 via a bracket 4. The bracket 4 is made of UV-resistant metal or high-strength polymer material and is fixed to the frame of the curved photothermal reflector 3 to ensure stability.

[0212] When the back photovoltaic cell 2 is a flexible photovoltaic cell, the specific method for attaching the back photovoltaic cell 2 to the back of the curved photothermal reflector 3 is as follows:

[0213] a. Pre-treatment of the back side of the curved photothermal reflector 3

[0214] Ensure that the back of the curved photothermal reflector 3 is clean, flat, and has good adhesion properties;

[0215] For surface cleaning: Use a lint-free cloth dampened with anhydrous ethanol or isopropanol to clean the back of the curved photothermal reflector 3 to remove dust, oil, and other impurities. If there is an oxide layer or uneven areas on the surface, it can be gently sanded with fine sandpaper (such as P1000).

[0216] Surface activation: The back surface of the back photovoltaic cell 2 can be activated using a plasma processor or ultraviolet ozone (UV-Ozone) device to improve its adhesion. If no such device is available, a primer containing an activator can be applied to the back surface of the back photovoltaic cell 2.

[0217] Surface drying: Allow the treated surface to air dry naturally at room temperature, or use hot air to dry it (temperature not exceeding 80°C).

[0218] b. Preparation of the rear photovoltaic cell 2

[0219] Ensure that the back photovoltaic cell 2 is in close contact with the back of the curved photothermal reflector 3.

[0220] Size cutting: The shape of the flexible photovoltaic cell is designed according to the size and curvature of the curved solar thermal reflector 3, and then precisely cut.

[0221] Check the back electrode: Ensure that the back electrode of the back photovoltaic cell 2 is flat and free of scratches or peeling.

[0222] Clean the surface of the back photovoltaic cell 2: Use a soft, lint-free cloth to clean the adhesive side of the cell, ensuring it is free of dust or oil.

[0223] c. Selection and application of adhesives

[0224] Using a suitable adhesive ensures long-term adhesion between the back photovoltaic cell 2 and the curved photothermal reflector 3, while meeting the requirements for thermal conductivity, anti-aging and flexibility.

[0225] Adhesive selection: Use silicone adhesives with high thermal conductivity (such as Dow Corning 3145) or epoxy resin adhesives (such as 3M 2216).

[0226] Uniform adhesive application: Apply a thin, uniform layer of adhesive (0.1-0.3 mm thick) to the back of the curved photothermal reflector 3, using a scraper or automatic adhesive application equipment to ensure consistent adhesive layer thickness.

[0227] Eliminate air bubbles: After coating, gently remove air bubbles using a vacuum degassing device or a scraper.

[0228] d. Attaching the second photovoltaic cell to the back

[0229] Alignment and positioning: Align the back photovoltaic cell 2 with the marked position on the back of the curved photothermal reflector 3, ensuring that the edges are aligned, and slowly attach it from one side to the other to avoid creating air bubbles.

[0230] Pressure bonding: Use a rubber roller or flat tool to apply pressure gently to ensure that the back photovoltaic cell 2 is completely bonded to the surface of the curved photothermal reflector 3. For large-area bonding, a negative pressure adsorption device can be used to apply pressure.

[0231] e. Curing process

[0232] The adhesive achieves maximum adhesion strength through a curing process.

[0233] Room temperature curing: For low-temperature adhesives, the bonded components should be left at room temperature for 24-48 hours.

[0234] Heat curing: If using epoxy resin or high-temperature curing silicone, the components can be placed in an oven at 60-80℃ for 2-4 hours to cure.

[0235] Cooling and Inspection: After curing, allow the components to cool naturally to room temperature and check for adhesion to ensure there is no lifting, bubbling, or peeling.

[0236] f. Encapsulation and Protection

[0237] Improve the durability and environmental adaptability of photovoltaic modules.

[0238] Edge sealing: Apply waterproof sealant (such as silicone sealant) to the joint between the back photovoltaic cell 2 and the curved photothermal reflector 3 to prevent moisture from seeping in.

[0239] Surface coating protective layer: If enhanced weather resistance is required, a transparent protective film (such as ETFE) can be added to the outer layer of the flexible photovoltaic cell.

[0240] When the back photovoltaic cell 2 is a rigid photovoltaic cell, it can be fixed to the bottom of the curved solar thermal reflector 3 by means of adhesive, hinges, clips, etc., including various structural forms such as a horizontal single back photovoltaic cell, an oblique single back photovoltaic cell, oblique multiple back photovoltaic cells, and horizontal and oblique multiple back photovoltaic cells. The specific selection and determination of parameters such as the angle of the installation components can be based on the light intensity and light angle of different regions.

[0241] This invention further verifies the performance advantages of the most preferred photovoltaic / photothermal / photovoltaic hybrid structure through experimental testing and simulation calculations. Studies show that the photovoltaic / photothermal / photovoltaic hybrid structure of this invention performs well under typical solar radiation conditions (illuminance of 1000 W / m²). 2The total energy conversion efficiency (based on the standard AM1.5 spectrum) can reach 45%-50%, which is 10%-20% higher than the average efficiency (25%-35%) of traditional split photovoltaic or solar thermal systems. Among them, the photoelectric conversion efficiency of the upper rigid semi-transparent photovoltaic cell can reach 15%-20% for ultraviolet and visible light.

[0242] Furthermore, the utilization rate of ambient light and ground-reflected light in the back photovoltaic cell 2 is improved by 20%-30%. Combined with the design of the nanostructured light-trapping layer 9, the light absorption capacity of the back photovoltaic cell 2 is increased by 10%-15% compared to ordinary cells without the light-trapping layer 9, and the power generation efficiency is improved by approximately 5%-8%. Experimental data shows that at an ambient light intensity of 200W / m², [the efficiency is improved]. 2 Under low light conditions, the additional power generation of the back photovoltaic cell 2 accounts for 8%-10% of the total power generation of the system, significantly enhancing the low-light performance of the overall system.

[0243] In terms of thermal management, the adoption of the thermally conductive layer 8 design reduces the operating temperature of the photovoltaic cell by 15-20℃ compared to traditional designs. According to accelerated life testing results, the temperature reduction effectively extends the lifespan of the photovoltaic cell, increasing fatigue life by 25%-30%. For example, under continuous operation at 70℃, the efficiency of ordinary photovoltaic cells decreases by about 5% due to thermal degradation, while the efficiency of the photovoltaic cell of this invention decreases by only 2%.

[0244] In summary, this utility model achieves efficient and comprehensive utilization of solar energy through structural innovation and performance optimization, and significantly improves system efficiency, light absorption capacity and battery life, demonstrating superior technical indicators and economic benefits, and is of great promotional value.

[0245] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A photovoltaic / solar thermal / photovoltaic roof-type composite structure, characterized in that, The device includes a rigid semi-transparent photovoltaic cell (1), a curved photothermal reflector (3), and a back photovoltaic cell (2) arranged sequentially from top to bottom. The back photovoltaic cell (2) includes either a flexible photovoltaic cell or a rigid photovoltaic cell. The flexible photovoltaic cell is tightly attached to the curved photothermal reflector (3), and at least one point of the rigid photovoltaic cell is tightly attached to the curved photothermal reflector (3).

2. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 1, characterized in that, A heat-conducting layer (8) is provided on the side of the back photovoltaic cell (2) close to the curved photothermal reflector (3), and a light-capturing layer (9) is provided on the inside of the back photovoltaic cell (2) and / or on the outer surface of the side away from the curved photothermal reflector (3).

3. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 2, characterized in that, The outer surface of the back photovoltaic cell (2) away from the curved photothermal reflector (3) is further provided with a low-reflection anti-reflection layer (10) and a diffuse reflection scattering layer (11), wherein the low-reflection anti-reflection layer (10) is close to the back photovoltaic cell (2) or the light-catching layer (9).

4. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 2, characterized in that, The thermally conductive layer (8) is a graphene film or alumina nanosheet, and the thermally conductive layer (8) is attached to the back of the back photovoltaic cell (2) by a thermally conductive adhesive.

5. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 2, characterized in that, The light-catching layer (9) is disposed on the outer surface of the back photovoltaic cell (2) away from the curved photothermal reflector (3). The light-catching layer (9) is a periodic nanopillar, nanopore array or randomly distributed nanoparticle structure, and the material of the light-catching layer (9) is indium tin oxide or zinc oxide.

6. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 2, characterized in that, The light-catching layer (9) is disposed on the light-absorbing layer (15) of the back photovoltaic cell (2), and the light-catching layer (9) is a nanostructure induced by femtosecond laser on the light-absorbing layer (15) of the back photovoltaic cell (2).

7. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 2, characterized in that, The light-trapping layer (9) is disposed on the electron transport layer (14) of the back photovoltaic cell (2), and the light-trapping layer (9) is a light-trapping nanostructure.

8. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 2, characterized in that, The light-catching layer (9) is disposed between the glass and the top encapsulation layer (12) in the back photovoltaic cell (2), and the light-catching layer (9) is a nano high-transmittance color film layer.

9. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 3, characterized in that, The low-reflection antireflection layer (10) is a Bragg mirror formed by alternating deposition of high-refractive-index and low-refractive-index materials.

10. The photovoltaic / photothermal / photovoltaic roof-type composite structure according to claim 3, characterized in that, The diffuse reflection scattering layer (11) is made of aluminum oxide or titanium dioxide nanoparticles.

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